Natural history of at-risk Lynch syndrome family members with respect to adenomas.

Our goal is to determine colon cancer surveillance strategy in patients at risk for Lynch's syndrome. Asymptomatic persons at 50% risk of having Lynch syndrome (age 25-70 years) were enrolled in colonoscopic screening. Those without adenomas were asked to return in one year. Those with adenomas were asked to return in six months because of concern for rapid malignant degeneration. Results: Twenty-five males and thirty females participated. On initial exam, eight of fifty-five patients (14.5%) had adenomas. Logistic regression showed a significant effect of age on the probability of finding adenomas at initial examination (p < 0.02). Followup was available in 27 patients (mean 35.5 months). Kaplan-Meier estimation of time to finding new or previously missed adenomas was 58 months for patients clear on first colonoscopy and 16 months for patients who had adenomas on first exam (p < 0.01). One adenocarcinoma has been found arising in a tubulovillous adenoma. Conclusion: The short-term risk of colorectal cancer in Lynch syndrome relatives without adenomas is low, as is the risk in those who have had all visualized adenomas removed.